Personal computer (PC) power consumption is a concern because of the sheer number of these power consuming devices. A large organization may have thousands of personal computers. Usually, a PC is equipped with a monitor. Power may not be efficiently used by PC monitors when they are left on overnight, when their screens are lit at an unnecessarily high intensity, or when the PCs are unused for extensive periods of time. Because of the scale involved, small power consumption savings on a PC by PC basis may result in huge costs for a large organization. Not only may large organizations benefit from power consumption savings, but an individual consumer may appreciate reducing power consumption and cost.
Current methods to conserve power only have a maximum of four power conservation modes. Current methods rely on the absence of one or both of the horizontal and vertical sync signals to the monitor to enter a lower power state. When the two sync signals are used as control bits, four power savings states are possible. With four power modes, there may be an on mode which does not save any power, a rapid recovery standby mode which may save 20% power, a slow recovery suspend mode which may save 80% power, and an off mode which may save nearly all power. However, these modes do not adequately adjust to changes in ambient light level, time of the day operations, and the like.
Aside from having a limited number of power conservation modes, current methods restrictively limit the time granted to respond to video signal line interruptions from an external processor, such as from a central processing unit of a computer. By relying on vertical and horizontal sync signals, the period of time to respond to a PC communications anomaly is limited from about 5 milliseconds to approximately 20 milliseconds because sync signals are regularly transmitted on a 50 Hz to 150 Hz basis. In certain situations, a time period of 20 milliseconds is too short to allow for PC anomaly correction such as when a user corrects a loose video cable connection. Even a simple solution to extend the time before a monitor enters a power conservation mode may require costly and time consuming hardware changes in retrofitting the monitor. Furthermore, when a computer system locks up for any reason, it can no longer perform useful work, yet its graphics subsystem still generates horizontal and vertical sync, hence not entering a lower power state.
Consequently, it would be desirable to have a greater number of power savings states in a monitor for providing precise power conservation levels. It would also be desirable to retrofit an existing monitor having four or fewer power conservation modes without changing hardware to save on installation costs.